江苏徐州西村金伯利岩管地质特征及其找矿意义
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摘要
西村岩管是在苏北地区发现的第一个金伯利岩管,颠覆了苏北地区无金伯利岩的历史。从岩石学、地球化学和伴生矿物等方面分析了西村岩管的地质特征,并进一步探讨其金刚石找矿意义。从区域背景和金刚石形成条件看,西村地区具备了金伯利岩侵位和金刚石矿形成的基本地质条件,而西村岩管为金刚石矿就位提供了母岩条件;西村金伯利岩与山东、辽宁金伯利岩具有相似的地球化学特征,是幔源岩浆低程度部分熔融的产物,且在岩浆上升过程中普遍遭受了壳源物质的混染,后期碳酸盐化现象普遍发育;其相容元素含量与山东金伯利角砾岩相似,均为典型的金伯利岩型配分模式,稀土元素表现为轻、重稀土元素强烈分馏的特征;伴生指示矿物主要为榴辉岩型含铬镁铝榴石、富铬透辉石和富镁铬尖晶石,其特征均表现出含矿金伯利岩的特点。
The Xicun kimberlite pipe was discovered for the first time which has ended the kimberlite-nonexistent history in northern Jiangsu Province. The geological characteristics of Xicun pipe were analyzed by petrology, geochemistry and associated minerals, and the prospecting significance was discussed. According to the regional background and the conditions of the diamond formation, it is considered that there existed basic geological conditions for kimberlite emplacement and diamond ore formation in Xicun area. The Xicun kimberlite pipe provided mother rock conditions for diamond ore. The Xicun kimberlites have similar geochemical characteristics to Shandong and Liaoning kimberlites. They were all formed by low degree partial liquation of the mantle-derived magma. Besides, they suffered hybridism of the earth crust in the process of magma rising and widespread carbonatization in the late period. The values of compatible elements are similar to those of Shandong kimberite breccia, which constitute the typical patterns of kimberlite. The heavy and light rare earth elements are characterized by strong fractionation.Associated indicator minerals include eclogite-type pyrope, chrome-rich diopside, and magnesium-rich chrome spinels, which show the characteristics of ore-bearing kimberlite.
The Xicun kimberlite pipe was discovered for the first time which has ended the kimberlite-nonexistent history in northern Jiangsu Province. The geological characteristics of Xicun pipe were analyzed by petrology, geochemistry and associated minerals, and the prospecting significance was discussed. According to the regional background and the conditions of the diamond formation, it is considered that there existed basic geological conditions for kimberlite emplacement and diamond ore formation in Xicun area. The Xicun kimberlite pipe provided mother rock conditions for diamond ore. The Xicun kimberlites have similar geochemical characteristics to Shandong and Liaoning kimberlites. They were all formed by low degree partial liquation of the mantle-derived magma. Besides, they suffered hybridism of the earth crust in the process of magma rising and widespread carbonatization in the late period. The values of compatible elements are similar to those of Shandong kimberite breccia, which constitute the typical patterns of kimberlite. The heavy and light rare earth elements are characterized by strong fractionation.Associated indicator minerals include eclogite-type pyrope, chrome-rich diopside, and magnesium-rich chrome spinels, which show the characteristics of ore-bearing kimberlite.
引文
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[20]杨德彬,许文良,裴福萍,等.徐淮地区早白垩世adakitic岩石的年代学和Pb同位素组成:对岩浆源区与华北克拉通东部构造演化的制约[J].岩石学报,2008,24(8):1745-1758.
[2]蔡逸涛,陈国光,张洁,等.安徽栏杆地区橄榄辉长岩地球化学特征及其与金刚石成矿的关系[J].资源调查与环境,2014,35(4)245-253.
[3]刘瑞.中国东部碱性基性岩与金刚石矿床成矿机制研究[J].长春工程学院学报(自然科学版),2003,4(4):1-4.
[4]张培元.论金刚石的成因和成矿作用及找矿方向[J].地质科技管理,1999,4(4):28-36.
[5]贺世杰.徐州地区晚元古代辉绿岩墙岩石成因的初步研究[D].中国科学院广州地球化学研究所硕士学位论文,2003.
[6]Mitchell R H.Kimberlites mineralogy geochemistry and petrology[M]New York:Plenum Press,1986:1-422.
[7]杨占兴,王彬娜.辽宁瓦房店30号金伯利岩管地球化学特征及金刚石矿床成因[J].世界地质,2016,35(2):378-386.
[8]董振信.中国金伯利岩地球化学[J].中国地质科学院院报,199123(2):99-114.
[9]宋瑞祥.中国金刚石矿床专论[M].北京:地质出版社,2013:12-225.
[10]杨学明,杨晓勇,陈双喜.岩石地球化学[M].合肥:中国科学技术大学出版社,2000:121-123.
[11]董振信.我国金伯利岩稀土元素特征[J].岩石矿物学杂志,1982,11(2):125-134.
[12]董振信.我国金伯利岩及其他岩类中的镁铝榴石[J].矿物学报,1981,(4):219-229.
[13]张广城.我国金伯利岩中镁铝榴石的化学成分特征及找矿意义[J].矿物岩石,1981,(Z1):118-126.
[14]张安棣.金刚石找矿指示矿物研究及数据库[M].北京:科学技术出版社,1991:1-162.
[15]郑建平,路凤香.金刚石中的流体包裹体研究[J].科学通报,1994,39(3):253-256.
[16]迟广成,伍月,胡建飞.山东蒙阴金伯利岩中石榴石特征及种类划分[J].岩石矿物学杂志,2014,33(5):877-884.
[17]董振信.中国金伯利岩中的单斜辉石[J].地质学报,1992,66(1):35-47.
[18]施建斌,曹强,蔡承刚.江苏新沂金刚石砂矿地质特征及供源方向探讨[J].化工矿产地质,2010,32(1):39-43.
[19]杨志军,梁榕,曾祥清,等.山东蒙阴金刚石多晶的显微红外光谱研究及其成因意义[J].光谱学与光谱分析,2012,32(6):1512-1518.
[20]杨德彬,许文良,裴福萍,等.徐淮地区早白垩世adakitic岩石的年代学和Pb同位素组成:对岩浆源区与华北克拉通东部构造演化的制约[J].岩石学报,2008,24(8):1745-1758.